Lenses of goggles used in skiing and the like are cooled by an outside air. The inside of the goggles is often filled with air which is warmer and more humid than the outside air due to heat emission from a wearer's body The goggles' role to prevent snow and wind from entering inside ends up with loss of air permeability. Further, if direct sunlight impinges on the goggles when the wearer is sweating, the sweat is evaporated to accelerate the above-mentioned tendency.
Under these circumstances, when the warm air generated within the goggles touches the lenses of the goggles cooled by the outside air, the lenses become fogged.
Therefore, as a method of preventing a lens surface from fogging, for example, Japanese Unexamined Patent Publication No.2004-292754 already discloses a method of providing a coating having hydrophilicity or a water-absorbing property on a lens surface, or a method of modifying the property of a lens surface.
Further, as another method of preventing a lens surface from fogging, for example, Japanese Unexamined Patent Publication No. 53-92593 discloses a method of warming up the entire lens by use of electricity.